[Nbd] [PATCH] nbd-server: fix server socket initialization

[=?UTF-8?q?Tuomas=20Jorma=20Juhani=20R=C3=A4s=C3=A4nen?= <tuomasjjrasanen@...1261...>]

Change the value for undefined descriptor from 0 to -1 because any value
greater or equal to 0 can be a valid file descriptor.

Signed-off-by: Tuomas Jorma Juhani Räsänen <tuomasjjrasanen@...1261...>
---
 nbd-server.c |   18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/nbd-server.c b/nbd-server.c
index f5aa6ca..ec617a9 100644
--- a/nbd-server.c
+++ b/nbd-server.c
@@ -2268,7 +2268,7 @@ int serveloop(GArray* servers) {
 	max=0;
 	FD_ZERO(&mset);
 	for(i=0;i<servers->len;i++) {
-		if((sock=(g_array_index(servers, SERVER, i)).socket)) {
+		if((sock=(g_array_index(servers, SERVER, i)).socket) >= 0) {
 			FD_SET(sock, &mset);
 			max=sock>max?sock:max;
 		}
@@ -2358,6 +2358,22 @@ int setup_serve(SERVER *serve) {
 	gchar *port = NULL;
 	int e;
 
+        /* Without this, it's possible that socket == 0, even if it's
+         * not initialized at all. And that would be wrong because 0 is
+         * totally legal value for properly initialized descriptor. This
+         * line is required to ensure that unused/uninitialized
+         * descriptors are marked as such (new style configuration
+         * case). Currently, servers are being initialized in multiple
+         * places, and some of the them do the socket initialization
+         * incorrectly. This is the only point common to all code paths,
+         * and therefore setting -1 is put here. However, the whole
+         * server initialization procedure should be extracted to its
+         * own function and all code paths wanting to mess with servers
+         * should initialize servers with that function.
+         * 
+         * TODO: fix server initialization */
+        serve->socket = -1;
+
 	if(!(glob_flags & F_OLDSTYLE)) {
 		return serve->servename ? 1 : 0;
 	}
-- 
1.7.10.4